Modern medicine uses many diagnostic and therapeutic procedures where electrical signals or currents are received or delivered to the patient's body. The interface between medical equipment used in these procedures and the skin of the patient is usually some sort of biomedical electrode. Such an electrode typically includes a conductor which must be connected electrically to the equipment. This connection typically includes a leadwire.
Among the diagnostic and therapeutic procedures using biomedical electrodes are transcutaneous electronic nerve stimulation (TENS) devices used for pain management, neuromuscular stimulation (NMS) used for treating conditions such as scoliosis, and monitors of electrical output from body functions, such as electrocardiagram (ECG) for monitoring heart activity and for diagnosing heart abnormalities.
For each diagnostic or therapeutic procedure, at least one electrode having an electrically conductive gel or adhesive is adhered to the body at the location of interest and electrically connected to diagnostic or therapeutic equipment. Ease of assembly and dissembly of the electrode from electrical connection to the diagnostic or therapeutic equipment is desired. But firm and continuous electrical connection is desired while the diagnostic or therapeutic procedure continues.
For example, in the case of TENS devices, two adhesive-bearing electrodes are adhered to the body where stimulation is desired but must be connected to a generator which provides a series of stimulating electrical pulses.
Conventionally, biomedical electrodes are disposable to preserve sanitary conditions and because such electrodes are generally inexpensive. However, for biomedical electrodes having detachable leadwires, the more expensive leadwires connecting the electrodes to the diagnostic or therapeutic equipment are often intended to be reused.
An example of a disposable electrode, reusable leadwire system is disclosed in coassigned U.S. Pat. No. 4,715,382 (Strand), which shows a disposable electrode adapted to be used with a reusable leadwire having a flat leadwire releasably attachable to a portion of the electrode. Additionally, coassigned U.S. Pat. No. 4,899,754 (Bly et al) discusses an electrode which has specific provision for the removal of the reusable leadwire having a flat contour for releasable insertion into a portion of the flat, conformable biomedical electrode.
Bayonet or male/female electrical connector systems have been developed for electrical devices where secure but releasable connection is desired.
U.S. Pat. No. 4,192,567 (Gomolka); U.S. Pat. No. 4,245,881 (Michaels); and U.S. Pat. No. 4,632,496 (Williams) all disclose electrical connectors where a bayonet or male prong is held within the coils of a helical conductor in a rigid receptacle. The gripping force on the bayonet or male prong is provided by the restoring radial force in the coiled helical conductor, and not by the receptacle housing.
U.S. Pat. No. 4,221,457 (Allen et al) discloses a helical conductor which may be temporarily held in an expanded state, e.g., by solder, but eventually the grip on the male portion of the connection is achieved by the restoring radial force in the radially shrinkable coil member.
U.S. Pat. No. 2,623,085 (Gier, Jr) and U.S. Pat. No. 3,587,034 (Canell) both disclose covers, such as shrouds or caps made of resilient material, about helical or coiled electrical connectors. But the covers provide insulation, not a radial force to grip a male portion of electrical connector.
U.S. Pat. No. 4,205,888 (Wade) discloses an electrical cable surrounded by flexible tubular interlocked metallic armor having a heavy gauge metallic wire connector member helically wound about the armor and serving as a grounding connector at its projecting terminus. Over this metallic construction is a flexible, resilient nonmetallic material serving as a sleeve to secure the cable construction to an electrical panel. The side walls of the sleeve tightly engage the side walls of the armored cable to provide a substantially permanent connection.
Care should be taken to provide a means of electrical connection which will not damage normally reusable leadwires due to excessive handling.